Mounting arrangement for electron discharge devices



March 29, 1949. c. H. FOULKES I MOUNTING ARRANGEMENT FOR ELECTRON DISCHARGE DEVICES Filed April 15, 1945 C/f r/kfq erfiim Era/ks By Patented Mar. 29, 1949 UNITED sm te TENT OFFICE MOUNTING ARRANGEMENT FOR ELECTRON DISCHARGE DEVICES Application April 13, 1945, Serial No. 588,211 In Great Britain April 7, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires April 7, 1963 4 Claims.

The present invention relates to mounting arrangements for electron discharge devices and in particular for those devices in which an electron beam is generated and iocussed by a magnetic field.

In electron velocity modulation tubes inv which resonators are excited by firing a beam of electrons therethrough (for example in a device of the kind disclosed in Patent Specification 2,320,860), it is often desirable to focus the beam by applying a magnetic field of suitable strength in which the lines of force are substantially parallel to the beam. This is usually done by mounting the tube or device between the poles of a magnet. These tubes are often manufactured in a form not unlike an ordinary thermionic valve so that replacements can be easily made. It has, however, been found difiicult to ensure that the necessary coincidence between the directions of the electron beam and of the magnetic field is maintained after a replacement, since this requires the use of appropriate test apparatus or indicators operated by trained personnel, which may be impracticable when replacements have to be made in apparatus operated in the field away from a factory or laboratory.

The present invention is directed towards the remedying of this difiiculty by providin the tubes which have to be replaced with mounting means which is adjusted before leaving the factory or laboratory, so that replacements may be made in the field without the use of special apparatus, or by skilled operators.

According to the invention, there is provided an adjustable clamp for holding an electron discharge tube in the field of a magnet, comprising means for mounting the clamp on the poles of the magnet so that when the tube is in the clamp, the axis of the tube is at right angles to the magnetic lines of force, the clamp being adapted to allow the tube to be rotated about the said axis.

The invention may also comprise an electron discharge tube of the kind in which an electron stream is operated in the field of a magnet, provided with a clamp for holding the tube between the poles of the magnet in such a manner as to allow the tube to be rotated about an axis for the purpose of adjusting the orientation of the electron stream in the field, the clamp being adapted to be mounted on the said poles.

This invention may further comprise an electron discharge tube having means for directing an electron beam transversely to the axis of a co-axial line resonator, provided with a clamp adapted for holding the tube while allowing it to be rotated about the said axis in the field of a magnet, so that the said beam may be set parallel to the said field, meansbeing provided for mounting the clamp on the poles of the magnet.

The invention will be described with reference to the accompanying drawing, in which Fig. 1 shows a perspective View of an adjustable mounting clamp, and Fig. 2 shows a perspective view of an electron discharge tube mounted between the poles of a magnet by means of the clamp shown in Fig, 1.

The electron discharge tube I shown in Fig. 2 comprises a cylindrical envelope 2 mounted on a base 3 which carries terminal pins l adapted to engage a socket arrangement 5 in the manner common in valve practice. The tube 11 may contain a co-axial line resonator arranged co-axially with the envelope 2 and excited by a transverse electron beam in the manner described in the above mentioned specification.

The focussing magnetic field is produced by a magnet l9, and the tube 6 is mounted between the poles of the magnet by means of the clamp H, which is adapted to rest on the poles in the manner indicated in Fig. 2 so that the tube l is in the desired position.

The clamp H comprises two similar halves l2, l3 fixed together by screws above and below, one of which is shown at M. A cylindrical channel iii is thus formed, into which the envelope 2 may be inserted, the tube being firmly gripped when the screws i i are tightened. Each half of the clamp is provided with a pair of side lugs I6 adapted to fit squarely on the pole pieces of the magnet Ill.

The clamp H may be a pressing of any nonmagnetic metal such as brass, or it may be a moulding in a synthetic resin, or the like. It may be fixed to the magnet in any convenient way, such as by springing inwards the side faces I! of the lugs, or by screws into the pole pieces arranged in any suitable way. One convenient and simple method is to fix a thin plate 20 of magneticmaterial to the underside 18 of each pair of lugs It, so that the clamp is held down by magnetic force. If desired, the side faces I! may in addition be sprun inwards, as already mentioned.

In order to prevent crushing of the envelope 2 when the clamp is being tightened, one or more layers of asbestos paper or other appropriate padding material is preferably placed round the envelope at it underneath the clamp.

Before being sent out, each tube is provided with a clamp H. The clamp is loosened sufliciently and placed with the tube on a magnet [0 which is a duplicate of the one in the apparatus in which the tube is to be used. The tube is then rotated until the electron beam is brought parallel to the magnetic field as indicated by appropriate test instruments connected to the tube. The clamp is then tightened, and the tube with clamp attached is then sent out. This ensures that when it is mounted in the apparatus on the magnet 19 as explained, the electron beam will be in the right direction, and thus the replacement can be made by any not specially skilled operator.

Although a co-axial line resonator has been cited as an example of a tube to which the invention is applicable, it is not restricted to this particular type. Any electron discharge tube requiring to be oriented with respect to a magnetic field could be similarly equipped, provided it can be conveniently designed with a cylindrical envelope. For example, the invention could be adapted to devices of the magnetron type.

What is claimed is:

1. An adjustable clamp for holding an electron discharge tube in the field of a magnet, comprising similar halves fastened together to form a cylindrical channel for embracing externally the envelope of the tube, the said halves being provided with means for mounting the clamp on the poles of the magnet.

2. An adjustable clamp according to claim 1, in which each of the said halves is provided with a pair of side lugs shaped to conform with one of the poles of the magnet.

3. .An adjustable clamp according to claim 1, in which the said halves are of non-magnetic material.

4; An adjustable clamp according to claim 1, in which 'each of the said halves is principally of non-magnetic material and is provided with a pair of side lugs shaped to conform with one of the poles -of the magnet, a plate of magnetic material being fixed to each pair of said lugs so as to come into contact with the corresponding pole of the magnet for holding the clamp thereon by magnetic force.

CHRISTOPHER HENRY FOULKES.

REFERENCES CITED The "following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,825,121 Owens Sept. 29, 1931 2,046,688 Kilgore July 7, 1936 

